Method for anchoring a mitral valve

ABSTRACT

An artificial mitral valve is anchored in the left atrium by placing the valve between the annulus of the natural mitral valve and an artificial annulus. The artificial annulus is formed by inserting a tool into the coronary sinus, and adjusting the tool to force the wall of the left atrium to form an annulus above the artificial valve, this locking it in place and forming a hemostatic seal.

BACKGROUND

1. Technical Field

The invention relates to minimally invasive cardiac surgery.

2. Description of the Related Art

The art of artificial heart valves is well known. Recently there is astrong interest in minimally invasive methods of replacing defectiveheart valves, and in particular in percutaneous deployment methods. Inthose procedures, the new valve is delivered and all the steps toinstall it, are performed via a fairly narrow catheter, typically 8-10mm diameter.

Replacing major surgery with the small incision needed for insertingsuch a catheter is a major step in cardiac surgery.

The mitral valve is a particularly difficult case as the heart has anunfavorable geometry for anchoring a replacement valve. In conventionalcardiac surgery the new valve is sutured to the tissue around thenatural valve, which is surrounded by an annular ring of more rigidtissue known as the valve annulus. This procedure is not practical forpercutaneous surgery. The main object of the invention is to devise ananchoring method for a replacement mitral valve. A further object ismaking the method both reversible and percutaneous.

BRIEF SUMMARY

An artificial mitral valve is anchored in the left atrium by placing thevalve between the annulus of the natural mitral valve and an artificialannulus. The artificial annulus is formed by inserting a tool into thecoronary sinus, and adjusting the tool to force the wall of the leftatrium to form an annulus above the artificial valve, thus locking theartificial mitral valve in place and forming a hemostatic seal. Theartificial mitral valve can be held by compression from above or bycircumferential compression from the tool. The compression can bereleased in order to remove the artificial mitral valve, if desired.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a longitudinal cross section of the heart, showing the leftand right atriums.

FIG. 2 is a longitudinal cross section of the heart as in FIG. 1,showing a deployed artificial mitral valve.

FIG. 3 is a longitudinal cross section of the heart as in FIG. 1,showing an artificial mitral valve anchored in place according to theinvention.

FIG. 4 is a general view of the anchoring tool.

FIG. 5 is a schematic view showing the use of the anchoring tool in apercutaneous operation.

FIG. 6A is a partial isometric view of the anchoring tool.

FIG. 6B is a side elevational view of a portion of the anchoring tool.

FIG. 7 is a schematic view showing the use of the invention in anchoringa balloon expandable valve.

DETAILED DESCRIPTION

Referring now to FIG. 1, the cross section of the upper part of theheart shows the left atrium 1, the right atrium 2, pulmonary veins 3 and4, tricuspid valve 5 and mitral valve 6, interventricular septum 7,atrioventricular septum 8, coronary sinus 10, interatrial septum 11, andtendon of Todaro 12. An artificial mitral valve 32 is introduced intothe left atrium to replace a defective mitral valve 6. The artificialmitral valve 32 is of flexible construction in order to be deployedpercutaneously via a catheter 38. For deployment the artificial mitralvalve 32 is compressed into an elongated oval shape. The art ofpercutaneous deployment is well known in minimally invasive surgery. Oneway to deploy the artificial mitral valve 32 is to pass catheter 38 viaseptum 11, after entering the right atrium via the superior vena cava.An anchoring tool 9 is shown in FIG. 1 already inside the coronary sinus10. The periphery of mitral valves 6 is less flexible and forms a shape39 known as the mitral valve annulus.

Referring now to FIG. 2, the artificial mitral valve 32 is allowed toexpand to its normal form. The artificial mitral valve 32 comprises ofvery flexible leaflets 34, and a less flexible annulus 33. The overallshape of the artificial mitral valve 32 is matched to the area above themitral valve annulus, which is generally “D” shaped. The cross sectionof the annulus can be round, oval, rectangular or any other shapesuitable for forming a hemostatic seal when seated above the annulus 39of the defective mitral valve 6 Annulus 33 can also be composed ofmultiple materials, some more rigid to better control the shape and somemore flexible to help if forming a hemostatic seal. For example, annulus33 can be made of soft silicone rubber with a Nitinol wire ring embeddedin the annulus to control the shape of the ring. The leaflets 34 can bemade of silicone rubber, Dacron or any other thin flexible materialwhich is compatible with the heart. Artificial mitral valves capable ofbeing delivered via a catheter are commercially available from EdwardsLife Sciences (www.edwards.com).

At this stage the anchoring tool 9 is in the coronary sinus but theanchoring tool 9 is left in the relaxed and flexible position, asexplained later on.

After the artificial mitral valve 32 is placed at the final locationabove the defective valve 3, the artificial mitral valve 32 has to beanchored into place. The artificial mitral valve 32 is brought into thecorrect position by using the delivery catheter to push the artificialmitral valve 32 downwards (this is also aided by the downwards bloodflow). To secure the artificial mitral valve 32 in place, a secondannulus, similar to the natural annulus 39 of the mitral valve 6, iscreated above the artificial mitral valve 32 by a ring-like anchoringtool 9 shown in cross section in FIG. 3. When anchoring tool 9 istightened it pulls in the outside wall of left atrium 1 as well asinteratrial septum 11 to form an almost full ring 36 around the valveannulus 33. This locks the artificial mitral valve 32 between thenatural annulus 39 of mitral valve 6 and an artificial annulus 36. Byfurther tightening anchoring tool 9 a hemostatic seal is established.Since valve annulus 33 is flexible (as is anchoring tool 9) it willconform to the exact shape of the natural annulus 39. Inside the rightatrium, tool 9 is placed against the interatrial septum 11 just abovetendon of Todaro 12.

Details of anchoring tool 9 are shown in FIG. 4. Anchoring tool 9 ismade of rigid links 25 connected by two flexible cables 26 and 27.Protrusions or barbs 28 can be added to increase anchoring in thecoronary sinus. A barb 24 is mounted on end piece 23. This barb iscovered by tube 21 of adjustment tool 15. When tube 21 is detached fromend piece 23, barb 24 springs open and secures the position of anchoringtool 9 relative to septum 11 (shown in FIG. 1). The shape of anchoringtool 9 is adjusted by tensioning cable 26 by turning screw 22 usingmatching socket 21 connected to inner flexible tube 19. Both anchoringtool 9 and flexible tube 15 have a hole for guide wire 18. Flexible tube19 can rotate freely inside flexible adjustment tool 15. Both adjustmenttool 15 and inner flexible tube are made of metal bellows type hose orof a braided hose, as these type hoses are torsionally stiff but easy tobend. It is desirable to make screw 22 and socket 20 of a ferromagneticmaterial, and provide a small rare-earth magnet (not shown) insidesocket 20. This facilitates locating screw 22 if adjustment tool 15 hasto be re-connected to anchoring tool 9 inside the heart.

Referring now to FIG. 5 and FIG. 4, the percutaneous use of anembodiment of the invention is shown. Anchoring tool 9 is attached toflexible adjustment tool 15 and is inserted into the right atrium 2 viacatheter 14, typically through the superior vena cava 13 over a guidewire 18. Guide wire 18 is inserted first, via ostium 37, all the way tothe end of the coronary sinus 10. Tools 9 and 15 are guided by the wire18. Anchoring tool 9 can be bent into shape by turning knob 17 whileholding shaft 16. Turning knob 17 will turn socket 20 and tighten cable26. To release adjustment tool 15, knob 17 is pressed into shaft 16causing tool 9 to be ejected from tube 21 and embed barb 24 in septum11. The operation is fully reversible as long as guide wire 18 is inplace. It is even possible to re-adjust or remove anchoring tool 9 at alater date, if socket 20 can be lined up with screw 22. This is assistedby magnetic attraction, as explained earlier. The reversibility of theoperation is a major advantage should the artificial mitral valve 32need to be removed.

The same tool can be used both as an adjustment tool for controllingregurgitation in a natural mitral valve and as an anchoring tool for anartificial mitral valve. This is important as in many cases anadjustment can correct the problem in the natural mitral valve, withoutneed for installing an artificial mitral valve. At a later date anartificial mitral valve may be required. In such a case, anchoring tool9 simply needs to be loosened, an artificial mitral valve installed andanchoring tool 9 re-tightened.

A more detailed view of anchoring tool 9 is given in FIGS. 6A and 6B.Each one of links 25 are cut at an angle 31. Angles 31 and length oflinks 25 determine the final shape of anchoring tool 9 when cable 26 isfully tightened. In order to keep links 25 in a single plane, the endsare cut in a V-shape as shown in insert drawing 40, which depicts a sideview of links 25. The V shaped cut can be aligned with the longitudinalaxis, as shown in 40, or can form an arbitrary angle to it. In such acase anchoring tool 9 will acquire a three-dimensional shape whentightened rather than fit in a single plane. Tightening screw 22 pullsnut 30 and tensions cable 26, causing anchoring tool 9 to tightentowards the final shape. The cross section of links 25 is designed toallow maximal blood flow in the coronary sinus. Cable 26 is permanentlyattached to nut 30 and to the last link (not shown), which is the linkfurthest away from end piece 23. Cable 27 is permanently attached to thelast link but not attached to end piece 23 in order to accommodate thechange in length when anchoring tool 9 is changing from straight tocurved. When cable 26 is loosened, anchoring tool 9 is very flexible,similar to a chain. When cable 26 is fully tight, anchoring tool 9 canexert considerable force (a few Kg) in the radial direction.

By the way of example, anchoring tool 9 is made of type 316 stainlesssteel, with links 25 having a cross section of about 2×3 mm, and alength of about 12 mm each. Each links has three holes about 1 mmdiameter each. Cables 26 and 27 are made of stainless steel as well andhave an outside diameter of about 0.8 mm. Screw 22 is made of 400 seriesstainless (to be magnetic) and is 2 mm diameter with 3 mm hex head.

The term “annulus” in this disclosure has to be broadly interpreted. Itneed not be a complete circle, as anchoring tool 9 encircles themajority of the artificial mitral valve circumference but not all of it,due to the presence of the aortic valve. The term “artificial annulus”should be understood as any arc-like retention feature formed byanchoring tool 9. Also, while the preferred embodiment shows theartificial annulus formed above the artificial mitral valve, it isobvious that the artificial annulus can be used to anchor the artificialmitral valve even without being above it. By the way of example, theperiphery of the artificial mitral valve can have a groove and theartificial annulus can engage this groove. In a different embodiment thebase of the artificial mitral valve can be wider than the top part, thusallowing anchoring by an artificial annulus. It is also clear that theanchoring tool 9 need not be made of individual links. The anchoringtool 9 can be made of an elastic material such as Nitinol and rely onthe elastic force to form the artificial annulus. While the term“anchoring” in this disclosure implies forming a hemostatic seal betweenthe artificial valve annulus and the existing mitral vale annulus, it isunderstood that the seal need not be perfect to practice the invention,as any small gaps tend to seal themselves over time due to formation ofscar tissue and deposits. A further improvement can be in the form ofadding magnets to the artificial valve annulus and adding ferromagneticmaterial to anchoring tool 9. This helps align the artificial mitralvalve 32 with the artificial annulus. While the force of the magnets maybe insufficient to retain the artificial mitral valve 32, it issufficient to hold in the correct position until anchoring tool 9 istightened.

An alternate way of using the artificial annulus is to use it as ananchoring base for a balloon expandable valve. Balloon expandable valvesare well known in the art and are used, for example, as replacementaortic valves. Until now they were not used as mitral valves since therewas no sufficiently rigid surface to expand the balloon against. FIG. 7shows use of an anchoring tool 9 to form a rigid artificial annulus 36,then expansion of a balloon mounted valve 42, mounted on balloon 41,into the rigid structure that was formed.

The various embodiments described above can be combined to providefurther embodiments. All of the commonly assigned US patent applicationpublications, US patent applications, foreign patents, foreign patentapplications and non-patent publications referred to in thisspecification and/or listed in the Application Data Sheet, including butnot limited to U.S. application Ser. No. 11/475,978, filed Jun. 28, 2006are incorporated herein by reference, in their entirety.

1. A method for anchoring an artificial mitral valve in a left atrium ofa heart, the method comprising: deploying the artificial mitral valve inthe left atrium of the heart; positioning the artificial mitral valveabove a natural annulus of a natural mitral valve in the heart; andshaping an atrial wall to form an artificial annulus to anchorartificial mitral valve.
 2. The method of claim 1 wherein shaping anatrial wall to form an artificial annulus includes shaping the atrialwall to form the artificial annulus at least one of above or around theartificial mitral valve.
 3. The method of claim 1, further comprising:percutaneously deploying the artificial mitral valve in the left atrium.4. The method of claim 1 further comprising: inserting a tool in thecoronary sinus to at least partially form the artificial annulus.
 5. Themethod of claim 1 wherein deploying the artificial mitral valve includesexpanding a balloon.
 6. The method of claim 1, further comprising:permanently installing a tool in the coronary sinus to at leastpartially form the artificial annulus.
 7. A method to replicate afunction of a natural mitral valve in a left atrium of a heart, thenatural mitral valve about which a coronary sinus of the heart at leastpartially extends, the method comprising: inserting an artificial mitralvalve inside an opening formed by the natural mitral valve in the leftatrium of the heart; inserting an elongate member in a flexible state atleast partially into the coronary sinus while in the flexible state suchthat the elongate member at least partially encircles a portion of theartificial mitral valve; and while the elongate member is at leastpartially in the coronary sinus, transitioning the elongate member fromthe flexible state to a more rigid state in which the elongate memberforms an artificial annulus to physically secure the artificial mitralvalve in the opening.
 8. The method of claim 7, further comprising:adjusting the elongate member during the installation in the heart; andremoving the elongated member from the coronary sinus at a later date.9. The method of claim 7 wherein the elongate member comprises aplurality of rigid links and a cable that connects the rigid links, andtransitioning the elongate member from the flexible state to a morerigid state includes tensioning of the cable.
 10. The method of claim 7,further comprising: percutaneously delivering the elongate member to theleft atrium of the heart via a detachable adjustment tool.
 11. Themethod of claim 7, further comprising: delivering the elongate membervia a catheter using an adjustment tool, and detaching the elongatemember from the adjustment tool to expose at least one elastic barb onthe elongate member.
 12. The method of claim 7, further comprising:delivering the elongate member via a catheter using an adjustment toolto which the elongate member is detachably magnetically coupled.
 13. Themethod of claim 7, further comprising: securing the artificial mitralvalve without sutures between said artificial annulus and the heart. 14.A method to replicate a function of a natural mitral valve in a leftatrium of a heart, a coronary sinus of the heart forming a pathextending at least partially about the natural mitral valve, the methodcomprising: percutaneously inserting an artificial mitral valve insidean opening formed by the natural mitral valve of the heart;percutaneously inserting an elongate member in a flexible state in thecoronary sinus; and percutaneously adjusting a dimension of the elongatemember to form an artificial annulus in the coronary sinus to physicallysecure the artificial mitral valve in the opening without any suturesbetween the artificial mitral valve and the heart.
 15. The method ofclaim 14, further comprising: delivering the artificial mitral valve andthe elongate member via a catheter.
 16. The method of claim 14 whereinthe elongate member comprises a plurality of rigid links and a cablethat connects the rigid links, and percutaneously adjusting a dimensionof the elongate member includes tensioning the cable.
 17. The method ofclaim 14 wherein percutaneously adjusting a dimension of the elongatemember includes tensioning the elongate member into the more rigid stateto apply a radially inward force to an annulus of the artificial mitralvalve via the coronary sinus to secure the annulus of the artificialvalve between a natural annulus of the natural mitral valve and theartificial annulus formed by the elongate member.
 18. The method ofclaim 14 wherein percutaneously adjusting a dimension of the elongatemember includes moving a tension adjustment coupler in one direction toincrease a tension in the elongate member or moving the tensionadjustment coupler in another direction to decrease the tension in theelongate member.
 19. The method of claim 18 wherein the tensionadjustment coupler is part of a magnetic coupler assembly, and furthercomprising: magnetically mating the magnetic coupler assembly with aportion of an adjustment tool which portion is at least partiallypercutaneously receivable in the heart.